The present application relates generally to electric vehicles such as, e.g., electric motorcycles, tricycles, and all-terrain vehicles (ATVs). More particularly, the application relates to methods and apparatus for preventing over-shifting on such vehicles.
One benefit of electric vehicles is the ability to re-capture energy during braking or on a downhill descent, often called regenerative braking—or “regen” for short. An electric motor, when supplied energy, will drive the traction wheel(s) of the vehicle, which then propel the vehicle forwards. When no energy is supplied to the motor, but the traction wheel(s) supply mechanical motion to the motor, the motor itself will become a generator supplying energy that can be used to assist in recharging the vehicle battery system. The higher the motor rotor is spun by mechanical means, the larger the voltage produced as a result.
For electric vehicles with a fixed gear system, the motor speed and corresponding output voltages are generally closely matched for the system it is designed into. With a gearbox equipped electric vehicle that supports selection between multiple gears, an issue arises that if a too low gear is quickly selected at high speeds, the resulting regen voltages become excessively large as the motor spins above maximum rated revolutions per minute (RPM). An example of this is a motorcycle with a multi-gear transmission traveling in one particular gear at maximum motor RPM, which then quickly downshifts one or more gears while maintaining the same or similar speed. The result would be the motor spinning faster than the maximum RPM speed allowed (overspin) with a resulting voltage generation that exceeds system design parameters (overvoltage), which can cause damage to the vehicle.